Submersible apparatus for measuring active fluorescence

Abstract

A submersible fluorometer for measuring a fluorescence of a photosynthetic material in a liquid, the fluorometer includes a set of light emitting diodes (LEDs) for supplying light to direct towards the liquid and a photodiode for measuring a detected light emitted from the liquid. The light is used for measuring the fluorescence of the photosynthetic material in the liquid. The fluorometer also has a water-tight volume for protecting the photodiode from the liquid.

1. A submersible fluorometer for measuring a fluorescence of a photosynthetic material in a liquid, the fluorometer comprising:
 a) a set of light emitting diodes (LEDs) for supplying light to direct towards the liquid, wherein said set of LEDs is for providing light for both saturating the photosynthetic material in the liquid and sampling the fluorescence of the photosynthetic material; 
 b) a photodiode for measuring a detected light emitted from the liquid, said detected light used for measuring said fluorescence of said photosynthetic material in the liquid; and 
 c) a first water-tight volume for protecting said photodiode from the liquid. 
 
   
   
     2. The submersible fluorometer of  claim 1 , wherein said first water-tight volume contains a printed circuit board. 
   
   
     3. The submersible fluorometer of  claim 1  further comprising a first set of at least one o-ring to seal said first water-tight volume. 
   
   
     4. The submersible fluorometer of  claim 3  further comprising a second set of at least one o-ring to seal said first water-tight volume. 
   
   
     5. The submersible fluorometer of  claim 1  further comprising a second water-tight volume containing a set of lenses. 
   
   
     6. The submersible fluorometer of  claim 5 , wherein said set of lenses comprises a lens for collimating light. 
   
   
     7. The submersible fluorometer of  claim 1 , wherein said set of light emitting diodes are in substantially a common plane. 
   
   
     8. The submersible fluorometer of  claim 7 , wherein said photodiode is aligned orthogonally to said common plane. 
   
   
     9. The submersible fluorometer of  claim 1 , wherein the set of light emitting diodes comprises a plurality of sampling light emitting diodes. 
   
   
     10. The submersible fluorometer of  claim 1 , wherein the set of light emitting diodes comprises a plurality of saturating light emitting diodes. 
   
   
     11. The submersible fluorometer of  claim 1  further comprising an emission filter between said liquid and said photodiode. 
   
   
     12. The submersible fluorometer of  claim 11  further comprising a lens for collimating light orthogonally to said emission filter. 
   
   
     13. The submersible fluorometer of  claim 1 , wherein said first water-tight compartment is for keeping said photodiode dry when said fluorometer is completely submerged in said liquid. 
   
   
     14. The submersible fluorometer of  claim 1  further comprising an aperture for blocking a direct line of sight between said set of LEDs and said photodiode. 
   
   
     15. The submersible fluorometer of  claim 1 , wherein each LED of said set of LEDs is for providing light for both saturating the photosynthetic material in the liquid and sampling the fluorescence of the photosynthetic material. 
   
   
     16. The submersible fluorometer of  claim 15 , wherein said each LED of said set of LEDs is for providing different brightness levels to produce light for said saturating and light for said sampling. 
   
   
     17. A submersible fluorometer for measuring a fluorescence of a photosynthetic material in a liquid, the fluorometer comprising:
 a) a set of light emitting diodes (LEDs) for supplying light to direct towards the liquid; 
 b) a photodiode for measuring a detected light emitted from the liquid, said detected light used for measuring said fluorescence of said photosynthetic material in the liquid; 
 c) a first water-tight volume for protecting said photodiode from the liquid; and 
 d) a second water-tight volume containing a printed circuit board. 
 
   
   
     18. The submersible fluorometer of  claim 17 , further comprising a plurality of o-rings to seal said first and second water-tight volumes. 
   
   
     19. A submersible fluorometer for measuring a fluorescence of a photosynthetic material in a liquid, the submersible fluorometer comprising:
 a) a set of sampling light emitting diodes for supplying a sampling excitation light to direct towards the liquid; 
 b) a set of saturating light emitting diodes for supplying a saturating excitation light to direct towards the liquid; 
 c) a photodiode for measuring a detected light emitted from the liquid in response to said sampling excitation light, said detected light used for measuring said fluorescence of said photosynthetic material in the liquid; and 
 d) an endcap sealing off a water-tight volume. 
 
   
   
     20. The submersible fluorometer of  claim 19 , wherein said water-tight volume contains electronics. 
   
   
     21. The submersible fluorometer of  claim 19  further comprising:
 a) a tubular housing for inserting said endcap; and 
 b) a set of at least one o-ring, wherein said set of at least one o-ring provides a water-tight seal between said tube and said endcap. 
 
   
   
     22. The submersible fluorometer of  claim 19 , wherein said submersible fluorometer is functional at depths of 500 or more meters below a surface of water. 
   
   
     23. The submersible fluorometer of  claim 19  further comprising a connector that screws into said endcap. 
   
   
     24. The submersible fluorometer of  claim 19 , wherein said submersible fluorometer measures fluorescence while said saturating LED is turned on. 
   
   
     25. A submersible fluorometer for measuring a fluorescence of a photosynthetic material in a liquid, the submersible fluorometer comprising:
 a) a set of sampling light emitting diodes for supplying a sampling excitation light to direct towards the liquid; 
 b) a set of saturating light emitting diodes for supplying a saturating excitation light to direct towards the liquid; 
 c) a photodiode for measuring a detected light emitted from the liquid in response to said sampling excitation light, said detected light used for measuring said fluorescence of said photosynthetic material in the liquid; and 
 d) an optical head for holding a set of optics, wherein said optical head is for sealing off a water-tight volume. 
 
   
   
     26. The submersible fluorometer of  claim 25  further comprising a set of o-rings around said optical head. 
   
   
     27. The submersible fluorometer of  claim 25 , wherein said set of optics comprises a collimating lens. 
   
   
     28. The submersible fluorometer of  claim 25 , wherein said set of optics comprises an emissions filter. 
   
   
     29. The submersible fluorometer of  claim 25  further comprising an LED holder within said optical head. 
   
   
     30. A submersible fluorometer for measuring a fluorescence of a photosynthetic material in a liquid, the fluorometer comprising:
 a) a sample chamber open to the liquid; 
 b) a photodiode for measuring a light from the sample chamber; 
 c) a transparent region of said sample chamber for allowing said light to reach said photodiode; and 
 d) a set of light emitting diodes (LEDs) for supplying light to the sample chamber, wherein the set of LEDs comprises a set of saturating LEDs for supplying light to said liquid and a set of sampling LEDs for triggering fluorescence of the photosynthetic material in the liquid. 
 
   
   
     31. The submersible fluorometer of  claim 30 , wherein the set of sampling LEDs and the set of saturating LEDs surround the sample chamber. 
   
   
     32. The submersible fluorometer of  claim 30 , wherein said sample chamber is surrounded by a transparent tube between said sample chamber and said set of LEDs.